1. Technical Field of the Invention
The present invention relates in general to the telecommunications field, and in particular, to a method and system for retaining and quickly restoring interrupted data communications in wireless communications systems.
2. Description of Related Art
Mobile wireless communication is becoming increasingly important for safety, convenience, and efficiency. One prominent mobile communication option is cellular communication. Cellular phones, for instance, can be found in cars, briefcases, purses, and even pockets. These cellular phones are capable of providing both circuit-switched voice connections and packet-switched data connections.
The circuit-switched voice connections are typically used to provide voice communication from a wireless subscriber to either another wireless subscriber over the associated wireless network system (e.g., a Public Land Mobile Network (PLMN)) or either a landline or an Integrated Services Digital Network (ISDN) subscriber over the Public Switched Telephone Network (PSTN). The packet-switched data connections may be used to transmit information packets directly to the wireless network system to which the cellular phone is currently in communication. The packet-switched data connections may alternatively be used as a conduit for forwarding information data packets from the wireless network system to a public network such as the Internet or to a private network such as a corporate local area network (LAN).
While both cellular communication and data packet transmission have been proliferating individually, the two technologies have been converging as well. For example, many subscribers to wireless networks now access the Internet or otherwise engage in data packet exchanges via their cellular phones or other wireless terminals. Wireless subscribers are thus able to send/receive data packets towards/from, for example, another PLMN or PSTN subscriber as well as engage in voice conversations over a PLMN or PSTN.
Subscribers to wireless network systems may additionally use their cellular phones to activate various services available from their cellular provider through the cellular communications system. Examples of such services are voice mail, call forwarding, and call waiting. In general, the call waiting service provides notification to a subscriber who is engaged in a first call that a second incoming voice call is being received by the cellular network. The subscriber may then choose to either ignore the notification or receive the second incoming voice call.
In some recently-developed wireless network systems, during packet-switched data connections, voice paging is permitted so that a subscriber may be notified when an incoming voice call is detected. In other words, a call-waiting-type feature can optionally be configured to interrupt packet-switched data connections in the event of an incoming circuit-switched voice call. Unfortunately, even in these few relatively modern cellular systems, interruption of the packet-switched data connection by an incoming circuit-switched voice call completely terminates the packet-switched data connection, including any negotiated computer communications protocol. Maintaining both the packet-switched data connection and the circuit-switched voice call at the same time requires a complicated and costly cellular phone that can operate (e.g., transmit/receive) on two channels (and probably two separate frequencies) simultaneously. As a result, when using standard cellular phones in conventional wireless networks, a subscriber must reacquire a packet-switched data channel and renegotiate a computer communications protocol in order to reestablish the interrupted data connection after completion of the interrupting voice call. There is a need, therefore, to be able to accommodate incoming voice calls during packet-switched data connections without relying on a complicated and costly cellular phone.
Renegotiation of the computer communications protocol governing the data communication can be time consuming. Furthermore, any currently executing packet applications are discontinued upon interruption and must therefore be reinitialized after reestablishing a packet-switched data connection. Moreover, the subscriber may experience difficulty renegotiating the computer communications protocol, thus leading to an extraordinary delay or even an inability to reestablish a packet-switched data communication.
In summary, conventional procedures in wireless communications systems do not enable a packet data communication to be quickly or easily reestablished after an interruption by, e.g., the acceptance of an incoming circuit-switched voice connection in response to a call-waiting-type of notification for the incoming circuit-switched voice connection.
The present invention provides a method and system for implementing a call-waiting-type service in which packet data communications may be retained upon interruption and quickly restored thereafter. The packet data communication retention call-waiting feature may be activated by the subscriber on either a permanent or a per-call basis. A retention activation request is preferably transmitted by a requesting mobile station (MS) as a packet data connection is initially being established.
The requesting MS first attempts to initiate a packet data uplink to a wireless network currently associated with the MS. Once acquired, a data terminal equipment (DTE) associated with the MS and the relevant wireless network negotiate a computer communications protocol such as a Point-to-Point Protocol (PPP). The mutually-understood computer communications protocol determines the framing and other parameters under which information is to be transmitted across a link from the subscriber""s DTE to a given point within the wireless network. For example, a dynamic data communication number (DCN) may be assigned to the DTE/MS when establishing a packet data communication. The PPP negotiation alone includes five phases, including the establish, authenticate, and network phases. Various encapsulation format options, for example, are determined for the PPP; information throughput is eventually possible in the network phase. Once the PPP link is negotiated, the DTE/MS may initiate user packet data transfer to/from the network.
When an incoming voice call notification message is received at the MS, the subscriber may decide to accept the incoming voice call. If accepted, then the packet data session is suspended by storing the negotiated parameters of the PPP (or other protocol) link. The negotiated parameters may be saved in memory at the DTE and in the wireless network. The MS, after accepting the incoming voice call, eventually terminates the voice call.
The voice call completion notification message triggers a reestablishment of the suspended packet data session using the retained information. The stored negotiated parameters are reactivated, and the link is restored without needing to renegotiate the PPP link. Additionally, any packet data applications that have not timed-out may be continued without reinitializing them.
An important technical advantage of the present invention is that subscribers are provided another option for a call-waiting-type service.
Another important technical advantage of the present invention is that a subscriber may establish a packet-switched data connection with an option to retain part of the packet-switched data connection upon experiencing an interruption.
Yet another important technical advantage of the present invention is that computer communications protocol parameters of a packet data communication can be saved when an MS/DTE of a subscriber receives, via the packet-switched data connection, a paging notification message for a circuit-switched voice call.
Yet another important technical advantage of the present invention is that the saved parameters of the packet data communication can be quickly and easily restored after discontinuing the circuit-switched voice call.